Author Topic: problems with calibration  (Read 17312 times)

smt-user

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problems with calibration
« on: October 18, 2011, 08:25:09 AM »
Hi to group

Recently i bought a second hand versatronics rv4s . I know nothing about p-p machines so i thought it was a good
starting point . I have run into  problems though that it fails to calibrate the pick up tools . The point is see is that
although i make the tools selection correctly when i press test i see the following .The head  goes between the rows of tools .The head  dives and then return to the top position . After that it issues a message "tool is already attached" retry (y/n)?. If i press "set" again it moves correctly to the correct tooltip position but "test" always fails  .Any ideas ?
The second question is regarding camera illumination . If i select the camera 2 checkbox in "calibration mode" the bottom camera leds illuminate. Should this not be the case for the other two cameras ?. When do the first,third camera leds illuminate ?. How can i check their operation?.
In any case is somebody willing to travel abroad in europe for a day or two to help me solve these problems and make a small pilot run ?.  

Gopher

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Re: problems with calibration
« Reply #1 on: October 18, 2011, 09:04:11 AM »
Hmm I have always stayed out of that menu simply because I couldn't follow my own notes I had made after watching a VSMT guy use it. However, are you quite sure you needed to go into these menu's in the first place? Is it possible you have now reset some values that only someone with a full calibration kit can put right?
However the error message is interesting the situation it would normally appear is this:

Machine finishes placing with Tool
Machine Return the tool to its slot
Tool Fails to disengage from the place head (perhaps because a component has dropped in its slot)
Machine checks there is no tool loaded by dropping the head between the two rows of slots to see if it hits the deck, it if does it throws that error and if it doesn't it loads the next tool.

From what you described the error I would expect is something like "Tool Load Error - Return to park position?" yes/no     (I could be remembering incorrectly it's not one I see all that often)

perhaps you have a dodgy encoder or something

You can test all solenoids, pumps, encoders etc using the utilities found in the versatronics directory.

You could try getting David clemets to see you, he did reopen his offer to service machines brifely in September, however when you add up mileage, daily rates +parts, you could probably buy a new machine.

Good luck hopefully someone on here knows their way around that Window.

smt-user

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Re: problems with calibration
« Reply #2 on: October 18, 2011, 09:28:23 AM »
Thank's for the answer Gopher.
This panel is presented during calibration. If you run calibration ->adjust tooltips and then "test" the tooltip goes between the tooltip rows i suspect to see if a tooltip is already in the head .After that if it senses (dive and up position) there is tooltip it issues message "tooltip already loaded"retry y/n?.I suspect if it senses there is no tooltip
it goes on to pickup the tool selected . Is there nowhere any information regarding setup or the utilities  ?.
What about the illumination of the cameras how can i check it ?.


Gopher

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Re: problems with calibration
« Reply #3 on: October 18, 2011, 09:42:48 AM »
If you go into c:\versatronics\rv\ you will see a variety of .exe files with names like armtest.exe, dsptest... etc how useful you find them is another question but they certainly turn lights on and off so you know they work.

phonoplug

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Re: problems with calibration
« Reply #4 on: October 18, 2011, 10:23:39 PM »
I get the "tooltip already loaded - retry y/n?." message from time to time when changing tools during a run. Baffled me the first few times as there clearly wasn't a tool loaded.

Turned out it was because the 'slot' used to home the R axis, which is also used as the overtravel sensor, was in the 'home' position at that point. That meant it was sensing an overtravel condition all the time while in that rotational position. So when the head goes down and back again in the middle of the tool holder, to check the previous tool was unloaded, it sensed overtravel making it think the tool was still present.

Simplest way out if this situation is to grab the r-axis and rotate it a notch or two. It doesn't put anything out and means the home slot is no longer in the position where it would sense overtravel when there isn't.

Make sense? I guess you have to have a good look around the head to see what I mean.

Gopher

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Re: problems with calibration
« Reply #5 on: October 18, 2011, 10:35:03 PM »
As an off-topic aside inspired by Phono's tip. If after placing is complete, you notice there is delay while the machine rotates the place head, this is a good indicator your tools all need a good cleaning with some light oil. Maybe blow out any dust with some compressed air etc.

phonoplug

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Re: problems with calibration
« Reply #6 on: October 18, 2011, 10:49:26 PM »
I don't doubt your wisdom Gopher, but whats the connection between oiling tools and the head rotating at the end of the run (which I do get quite a bit)? I'm baffled again!

Mike

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Re: problems with calibration
« Reply #7 on: October 18, 2011, 10:50:39 PM »
Re the OP's issue I guessed the switch that detects the head up/down status may be stuck in the up  position - this would make it think a tool was loaded when it wasn't.
Quote
As an off-topic aside inspired by Phono's tip. If after placing is complete, you notice there is delay while the machine rotates the place head, this is a good indicator your tools all need a good cleaning with some light oil. Maybe blow out any dust with some compressed air etc
Mine has always done this - why would an unclean tool make this happen? Tool changes still work fine.

phonoplug

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Re: problems with calibration
« Reply #8 on: October 18, 2011, 11:00:03 PM »
Mike - its not that the switch has got stuck in an up position. There is an optical slot sensor used for sensing R is 'home'. It has a second function though sensing overtravel, in which case the whole disk (that contains the slot) is pushed out the way of the sensor. Essentially this means that the machine cannot differentiate between a homed R and overtravel.

With the optical sensor outputing that it senses light, a) the R axis is either homed, OR b) overtravel is occurring, OR c) BOTH (a) and (b).

With the optical sensor outputing that no light is present at the detector, R axis IS NOT homed, AND there is no overtravel.

Well anyway thats true for my RV1s, non -s versions may be different.

Gopher

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Re: problems with calibration
« Reply #9 on: October 19, 2011, 07:57:53 AM »
Well it came straight from the mouth of our VSMT engineer who said "it's finding itself" . An educated guess is that its locating itself in that home position described by phono. Perhaps when the tools are a bit grubby the head does not actually rotate as much to free the tool as it expects it to?
Whatever the case, it  works and adds up to quite a bit of time saved if the problem has gotten chronic.    

Mike

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Re: problems with calibration
« Reply #10 on: October 19, 2011, 12:14:46 PM »
Thinking about it, could be due to the fact that the up/down is sensed with the same ring as rotation, so if picking up a tool results in enough up-force to push the ring up, it then assumes itmay have lost the rotational zero reference.

However why would it ever need an absolute reference for rotation anyway?

Gopher

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Re: problems with calibration
« Reply #11 on: October 19, 2011, 12:32:56 PM »
Ahh I think I can answer that, (however despite being surrounded by drive control manufacturers its not my field so I could be wrong) the more expensive your SM machine the better its motors and controls are. On modern high end machines you will find them bragging about 'linear' or 'servo' motors, entry level machines use stepper motors. The first 2 have continuous feedback so you always know where it is. With steppers you just say do 3 steps and assume that's what its done, this is why an RV is rammed full of limit switches and sensors..
Couple that with the fact they probably acknowledge the engineering in the machine not 100% and the only way you can be reasonably sure the nozzle and it aperture is always in about the right place is always to rotate it from the same 0 reference.
How did I do?

smt-user

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Re: problems with calibration
« Reply #12 on: October 19, 2011, 07:06:59 PM »
I had no success to find any solution by turning lightly the r axis head as phonoplug has suggested . After runing some other tests i noticed there was no power to the head camera leds . So my thinking is now that possibly a missing power connection is not enabling the leds and possibly a optocoupler with the same voltage origin controls  this point .  After checking for the power supply of the two leds beside the mirror i found a black , white cable in a 4 pin header in the arm board . The leds are powered through 2 resistors 470 ohms each  . Black goes to ground but white has a steady voltage of 1.4 volts. Does anybody know the origin of this power ???. Where does it come from and where can i trace it ? .The board outputs 12 and 9 volts and also accepts 5 volts from the pc . Any ideas ?????
 

Mike

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Re: problems with calibration
« Reply #13 on: October 19, 2011, 10:25:27 PM »
Quote
Ahh I think I can answer that, (however despite being surrounded by drive control manufacturers its not my field so I could be wrong) the more expensive your SM machine the better its motors and controls are. On modern high end machines you will find them bragging about 'linear' or 'servo' motors, entry level machines use stepper motors. The first 2 have continuous feedback so you always know where it is. With steppers you just say do 3 steps and assume that's what its done, this is why an RV is rammed full of limit switches and sensors..
Yes I know the RV uses open loop steppers, and needs limit sensors on the  arm and up/down axes, but rotation is always relative to the position the head is in when it picks up the tool, and has continuous 360 deg rotation, so why would you need an absolute reference for it?

Gopher

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Re: problems with calibration
« Reply #14 on: October 19, 2011, 10:27:51 PM »
Phonoplug has made a replacement Arm board that is all solid state so he knows his way around this particular board, so you may just be in luck.